Polymeric blends and articles made therefrom

ABSTRACT

A biaxially oriented film includes a PLA and polyolefin (PLA/PO) blend. The film has a haze of 80% or greater as measured by ASTM-D1003 and a 45° gloss of less than 50% as measured by ASTM-D-2457.

CROSS-REFERENCE TO RELATED APPLICATIONS

None

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable

BACKGROUND

1. Technical Field

This disclosure relates to polymeric compositions including abiodegradable polymer.

2. Background

Articles constructed from certain synthetic polymeric materials havewidespread utility, but may remain semipermanently in a naturalenvironment. Certain biodegradable polymers may be used in conjunctionwith these synthetic polymeric materials to form articles that maydegrade more rapidly than articles made solely with synthetic polymericmaterials.

SUMMARY

An embodiment of the present disclosure is directed to a biaxiallyoriented film. The biaxially oriented film includes a polylactic acidand polyolefin (PLA/PO) blend. The film has a haze of 80% or greater asmeasured by ASTM-D-1003 and a 45° gloss of less than 50% as measured byASTM-D-2457.

Another embodiment of the present disclosure is directed to a method ofproducing a biaxially oriented film. The method includes blendingpolylactic acid and a polyolefin to form a polymeric blend (PLA/POblend) having a ratio of PLA to PO in the blend between 4:1 and 199:1.The method further includes forming the PLA/PO blend into a film, andbiaxially orienting the film to form a film having a haze of 80% orgreater as measured by ASTM-D1003 and a 45° gloss of less than 50% asmeasured by ASTM-D-2457.

Yet another embodiment of the present disclosure is directed to anarticle. The article includes a polylactic acid and polyolefin (PLA/PO)blend having a ratio of PLA to PO in the blend of between 4:1 and 199:1,wherein the object is opaque.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and theadvantages thereof, reference is now made to the following briefdescription, taken in connection with the accompanying drawings anddetailed description, wherein like reference numerals represent likeparts.

FIG. 1A is graph of oven temperature versus haze as described in theExample.

FIG. 1B is a graph of oven temperature versus gloss as described in theExample.

DETAILED DESCRIPTION

A detailed description will now be provided. The description includesspecific embodiments, versions and examples, but the disclosure is notlimited to these embodiments, versions or examples, which are includedto enable a person having ordinary skill in the art to make and use thedisclosure when that information is combined with available informationand technology.

Various terms as used herein are shown below. To the extent a term usedin a claim is not defined below, it should be given the broadestdefinition skilled persons in the pertinent art have given that term asreflected in printed publications and issued patents at the time offiling. Further, unless otherwise specified, all compounds describedherein may be substituted or unsubstituted and the listing of compoundsincludes derivatives thereof.

Disclosed herein are polymeric compositions and articles made therefrom.In some embodiments, the polymeric compositions include polylactic acid(PLA).

Polylactic acid suitable for use in this disclosure may be of the typeknown in the art. For example, polylactic acid may includepoly-L-lactide (PLLA), poly-D-lactide (PDLA), poly-LD-lactide (PDLLA),or combinations thereof. Modified polylactic acid is also suitable foruse in this disclosure. Modified polylactic acid refers to stereocomplexpolylactic acid and surface-modified polylactic acid, as described inRahul M. Rasal et al., Poly(lactic acid) modifications, PROGRESS INPOLYMER SCIENCE 35 (2010) 338-356, which is incorporated herein fully byreference. Surface-modified polylactic acid includes, but is not limitedto, coated polylactic acid, polylactic acid with entrappedbiomacromolecules, polylactic acid blended with migratory additives,chemically conjugated polylactic acid, and polylactic acid that has beenphotografted. Polylactic acid may be prepared using any suitable methodknown to one or ordinary skill in the art. For example, polylactic acidmay be prepared by dehydration condensation of lactic acid, such asdescribed in U.S. Pat. No. 5,310,865, which is incorporated herein byreference in its entirety. Alternatively, polylactic acid may beprepared by synthesis of a cyclic lactide (also known as cyclic dimmer)from lactic acid followed by ring opening polymerization of the cycliclactide. An example of such a process is described in U.S. Pat. No.2,758,987, which is incorporated herein by reference in its entirety.

Catalysts may be used in the production of polylactic acid. Thecatalysts may be of any type suitable for the process. Examples of suchcatalysts include without limitation tin compounds such as tin octylate,titanium compounds such as tetraisopropyl titanate, zirconium compoundssuch as zirconium isopropoxide, and antimony compounds such as antimonytrioxide.

In an embodiment, a polylactic acid suitable for use in this disclosuremay have a density of from 1.238 g/cc to 1.265 g/cc, alternatively from1.24 g/cc to 1.26 g/cc, and alternatively from 1.245 g/cc to 1.255 g/ccas determined in accordance with ASTM D792; a melt index of from 5 g/10min. to 35 g/10 min. or alternatively from 15 g/10 min. to 30 g/10 min.,as determined in accordance with ASTM D1238 at a temperature of 210° C.and a load of 2.16 kg; a crystalline melt temperature of from 150° C. to180° C. or alternatively from 155° C. to 170° C.; a glass transitiontemperature of from 45° C. to 85° C., alternatively from 50° C. to 80°C., or alternatively from 55° C. to 60° C. as determined in accordancewith ASTM D3417; a tensile yield strength of from 4,000 psi to 25,000psi, alternatively from 5,000 psi to 20,000 psi, or alternatively from8,000 psi to 10,000 psi as determined in accordance with ASTM D638; atensile elongation of from 1.5% to 10%, alternatively from 2% to 8%, oralternatively of from 3% to 4% as determined in accordance with ASTMD638; a notched Izod impact of from less than 2 ft-lb/in, or between,0.1 ft-lb/in to 0.8 ft-lb/in or from 0.2 ft-lb/in to 0.7 ft-lb/in, asdetermined in accordance with ASTM D256. Examples of polylactic acidsuitable for use in this disclosure include without limitation PLA3251,PLA4202, and PLA6202, which are commercially available from Nature WorksLLC.

The polymeric composition of some embodiments of the present disclosureincludes a polyolefin as a cavitating agent. These polymeric blends arereferred to hereinafter as PLA/PO blends. A cavitating agent refers to acompound(s) capable of generating voids in the structure of film duringthe film-making process. Non-limiting examples of polyolefins suitableas cavitating agents in this disclosure include homopolymers andcopolymers of polypropylene and polyethylene or blends of polypropyleneand polyethylene. The polypropylene may be Ziegler-Natta or metallocenecatalyzed. The polypropylene may be a homopolymer, a random copolymer ofpolypropylene or a heterophasic copolymer. In certain embodiments wherethe polypropylene is a copolymer, the comonomer may be ethylene. Thepolyethylene may be a high density polyethylene (HDPE), low densitypolyethylene (LDPE) or linear low density polyethylene (LLDPE).

When the cavitating agent is HDPE, the polyethylene may have an MI2 ofless than 100 dg/min, or 0.1 to 5.0 dg/min, from 0.2 to 2.0 dg/min orfrom 0.4 to 0.7 dg/min or about 0.55 dg/min as measured by ASTM D-1238at a temperature of 190° C. and a load of 2.16 kg. The density of theHDPE for these embodiments may be from 0.940 to 0.970 g/cc, 0.945 to0.962 g/cc or about 0.946 g/cc as measured by ASTM D792. The peakmolecular weight (Mp) of the HDPE may be greater than 10,000 g/mol,40,000 g/mol, or greater than 50,000 g/mol as measured by GPC. Theweight average molecular weight (Mw) of the HDPE may be between 20,000and 200,000 or between 100,000 and 200,000 or between 130,000 and170,000, as measured by GPC. In certain embodiments, the polydispersity(Mw/Mn) of the HDPE may be between 2 and 15. Examples of such HDPEsuitable for use in this disclosure are HDPE 7194 manufactured by TotalPetrochemicals.

In some embodiments, the PLA/PO blend may include between 50 and 99.5%PLA and 0.5% to 50% PO; or between 80% and 99.5% PLA and 0.5% to 20% PO;or between 90 and 95% PLA and 10% to 5% PO. All composition ratios areby weight of the components. In certain embodiments, the ratio of PLA toPO in the PLA/PO blend is between 1:1 and 199:1 or between 4:1 and199:1, or between 9:1 and 19:1.

In certain embodiments of the present disclosure, the PLA/PO blend cancontain between 0.2% and 30%, 0.5% to 20%, and 1%-5% compatibilizers, byweight as a percentage of the PLA/PO blend. In certain embodiments, thecompatibilizer is maleic anhydride-modified polyolefins,styrene-ethylene/butylene-styrene (SEBS), an epoxy-modified polyolefin,or a combination thereof. In some embodiments, the only compatibilizerin the PLA/PO blend is a maleic anhydride-modified polyolefins,epoxy-modified polyolefin, SEBS or a combination thereof. Non-limitingexamples of epoxy-modified polyolefins include, but are not limited to,epoxy-functionalized polypropylene, epoxy-functionalized polyethylene,epoxy-functionalized polybutadiene and combinations thereof.

An example of an epoxy-functionalized polyethylene suitable for use inthis disclosure includes an ethylene-methacrylate copolymer, such aspolyethylene co-glycidyl methacrylate (PE-co-GMA), such as LOTADERAX8840, which is a PE-co-GMA containing 8% GMA that is commerciallyavailable from Arkema. Another example of a compatibilizer suitable foruse in this disclosure is POLYBOND 3200, which has 2.7% maleic anhydridecommercially available from Chemtura. An example of anepoxy-functionalized polypropylene is glycidyl methacrylate graftedpolypropylene (PP-g-GMA).

In certain embodiments when the compatibilizer is PP-g-GMA, the PP-g-GMAmay be prepared by any suitable method such as for example by graftingGMA onto polypropylene in the presence of an initiator such as peroxide.Examples of initiators suitable for use in this disclosure includewithout limitation LUPERSOL 101 and TRIGANOX 301, which are peroxidescommercially available from Arkema. In an embodiment, the initiator maybe used in an amount of from 0.03% to 2 wt. % by total weight of thePLA/PO blend, alternatively from 0.2 wt. % to 0.8 wt. %, alternativelyfrom 0.3 wt. % to 0.5 wt. %.

The grafting reaction of GMA onto PP may be conducted in a molten stateinside an extruder such as, for example, a single extruder or atwin-screw extruder. Hereinafter, such process is referred to asreactive extrusion. A feedstock including PP, GMA, and initiator (i.e.,peroxide) may be fed into an extruder reactor sequentially along theextruder, alternatively the feedstock (i.e., PP, GMA, and initiator) maybe pre-mixed outside and fed into the extruder.

In an alternative embodiment, the PP-g-GMA is prepared by grafting GMAonto polypropylene in the presence of an initiator and a modifier. Themodifier may be a multi-functional acrylate comonomer, styrene,divinylbenzene, and combinations thereof, for example. Themulti-functional acrylate comonomers may be polyethylene glycoldiacrylate, trimethylolpropane triacrylate (TMPTA), alkoxylatedhexanediol diacrylatete, and combinations thereof, for example.

The multi-functional acrylate comonomer may be further characterized bya high flash point. The flash point of a material is the lowesttemperature at which it can form an ignitable mixture in air, asdetermined in accordance with ASTM D93. The higher the flash point, theless flammable the material, which is a beneficial attribute for meltreactive extrusion. In an embodiment, the multi-functional acrylatecomonomer may have a flash point of from 50° C. to 120° C.,alternatively of from 70° C. to 100° C., alternatively of from 80° C. to100° C. Examples of multi-functional acrylate comonomers suitable foruse in this disclosure include without limitation SR256 (polyethyleneglycol diacrylate), CD560 (alkoxylated hexanediol diacrylate), and SR351(TMPTA), which are commercially available from Sartomer.

The grafting reaction of GMA onto polypropylene in the presence of aperoxide and the multi-functional acrylate comonomer polyethylene glycoldiacrylate is depicted in Scheme 1

Without wishing to be limited by theory, the hydrogens on the tertiarycarbon of polypropylene molecules can be easily abstracted in thepresence of peroxide during reactive extrusion, forming polypropylenemacroradicals with unpaired electrons. The polypropylene macroradicalswhich are generally unstable, tend to form free radicals through a stepreferred to as “β-scission.” β-scission refers to a family of reactionswherein bonds that are in a beta-position to a radical are cleavedresulting in the formation of a double bond and a new radical. Theβ-scission reaction is believed to be responsible mainly for theformation of internal double bonds thus its occurrence is correlatedwith the allylic content of the final polymer. β-scission is typicallyfavored over the grafting reaction (i.e. the addition of the GMA)resulting in both a lower grafting of GMA and a polypropylene having alower average molecular weight. However, in the reactions including amulti-functional acrylate comonomer, the multi-functional acrylatecomonomer may function to readily capture the polypropylenemicro-radicals resulting in the formation of a more stable intermediate(i.e., polypropylene-acrylate radicals). The relatively stablepropylene-acrylate radicals tend to react more readily with GMA, whichis an acrylate type monomer, and consequently favor the graftingreaction.

In addition, as shown in Scheme 1, multiple free radicals may exist onthe grafted propylene-acrylate molecules thus making it easier tocapture and initiate the reaction of GMA. The reactivity of GMA towardsacrylate free radicals may be higher than towards polypropylene tertiarymacro-radicals. Consequently, PP-g-GMA prepared using a reaction mixtureincluding a multi-functional acrylate comonomer may display a higherdegree of grafting than a PP-g-GMA prepared using an otherwise similarcomposition in the absence of a multi-functional acrylate comonomer.PP-g-GMA prepared using a multifunctional acrylate comonomer ishereinafter referred to as a highly grafted GMA (HGGMA).

In an embodiment, the HGGMA is prepared from a reaction mixtureincluding a polypropylene present in an amount of from 80 wt. % to 99.5wt. %, alternatively from 90 wt. % to 99 wt. %, or alternatively from 95wt. % to 99 wt. %; GMA present in an amount of from 0.5 wt. % to 20 wt.%, alternatively from 1.0 wt. % to 10 wt. %, or alternatively from 1.0wt. % to 5.0 wt. %; a multi-functional acrylate comonomer present in anamount of from 0.5 wt. % to 15 wt. %, alternatively from 1.0 wt. % to 10wt. %, or alternatively from 1.0 wt. % to 5.0 wt. %; and an initiatorpresent in an amount of from 0.05 wt. % to 1.5 wt. %, alternatively from0.2 wt. % to 0.8 wt. %, or alternatively from 0.3 wt. % to 0.5 wt. %.The ratio of GMA:multi-functional acrylate comonomer in the HGGMA mayrange from 1:5 to 10:1, alternatively from 1:2 to 5:1, or alternativelyfrom 1:1 to 3:1.

The amount of grafting of GMA onto the polyolefin may vary depending ona variety of factors such as the type of materials used and processingconditions. Such parameters may be varied by one of ordinary skill inthe art with the benefits of this disclosure to produce reactivemodifiers having a user-desired grafting yield.

The grafting yield may be determined using any suitable method. Forexample, the grafting yield may be determined by Fourier TransformInfrared Spectroscopy (FTIR) spectroscopy. In an embodiment, a methodfor determining the grafting yield includes obtaining the FTIR spectraof polymeric samples having a mixture of PP and GMA wherein the amountof each component is known. A calibration curve may be generated byplotting the signal intensity at one or more wavelengths as a functionof component concentration. The FTIR spectra of a PP-g-GMA sample maythen be determined and compared to the calibration curve in order todetermine the grafting yield. This method is described in more detail inAngew. Makromol. Chem, 1995, V229 pages 1-13 which is incorporated byreference herein in its entirety. In an embodiment, the HGGMA may have agrafting yield of from 0.2 wt. % to 15 wt. %, alternatively from 0.5 wt.% to 10 wt. %, or alternatively from 1.0 wt. % to 5.0 wt. %.

Other examples of compatibilizers are epoxy-modified polyolefins aremade via reactive extrusion with the PLA/PO blend. As used herein, theterm “reactive modifier” refers to polymeric additives that, when addedto the molten PLA/PO blend, form compounds in situ that serve tostabilize the PLA/PO blend. The compounds formed in situ compatibilizethe PLA/PO blend and the reactive modifiers are precursors to thesecompatibilizers.

In one or more embodiments, the reactive modifier is selected fromoxazoline-grafted polyolefins, maleated polyolefin-based ionomers,isocyanate (NCO)-functionalized polyolefins and combinations thereof,for example. The oxazoline-grafted polyolefin is a polyolefin graftedwith an oxazoline ring-containing monomer. In one or more embodiments,the oxazoline may include a 2-oxazoline, such as 2-vinyl-2-oxazoline(e.g., 2-isopropenyl-2-oxazoline), 2-fatty-alkyl-2-oxazoline (e.g.,those obtainable from the ethanolamide of oleic acid, linoleic acid,palmitoleic acid, gadoleic acid, erucic acid and/or arachidonic acid)and combinations thereof, for example. In yet another embodiment, theoxazoline may be selected from ricinoloxazoline maleinate,undecyl-2-oxazoline, soya-2-oxazoline, ricinus-2-oxazoline andcombinations thereof, for example. In yet another embodiment, theoxazoline is selected from 2-isopropenyl-2-oxazoline,2-isopropenyl-4,4-dimethyl-2-oxazoline and combinations thereof, forexample. The oxazoline-grafted polyolefin may include from about 0.1 wt.% to about 10 wt. % or from 0.2 wt. % to about 2 wt. % oxazoline, forexample.

The isocyanate (NCO)-functionalized polyolefins may include a polyolefingrafted with an isocyanate functional monomer. The isocyanate may beselected from TMI® unsaturated isocyanate (meta), meta andpara-isopropenyl-alpha, alpha-dimethylbenzyl isocyanate,meta-isopropenyl-alpha, alpha-dimethylbenzyl isocyanate,para-isopropenyl-alpha, alpha-dimethylbenzyl isocyanate and combinationsthereof, for example.

The maleated polyolefin-based ionomers may include a polyolefin ionomermaleated and then neutralized with a metal component. Maleation is atype of grafting wherein maleic anhydride, acrylic acid derivatives orcombinations thereof are grafted onto the backbone chain of a graftablepolymer. The metal component may be selected from sodium hydroxide,calcium oxide, sodium carbonate, sodium hydrogencarbonate, sodiummethoxide, sodium acetate, magnesium ethoxide, zinc acetate,diethylzine, aluminium butoxide, zirconium butoxide and combinationsthereof, for example. In one specific embodiment, the metal component isselected from sodium hydroxide, zinc acetate and combinations thereof,for example.

In one or more embodiments, the graftable polymer is a polyolefinselected from polypropylene, polyethylene, combinations thereof andcopolymers thereof.

In certain embodiments, the reactive modifiers may be formed by agrafting reaction. The grafting reaction may occur in a molten stateinside of an extruder, for example (e.g., “reactive extrusion”). Suchgrafting reaction may occur by feeding a feedstock sequentially alongthe extruder or the feedstock may be pre-mixed and then fed into theextruder, for example.

In one or more embodiments, the reactive modifiers are formed bygrafting in the presence of an initiator, such as peroxide. Examples ofinitiators may include LUPERSOL® 101 and TRIGANOX® 301, commerciallyavailable from Arkema, Inc., for example.

The initiator may be used in an amount of from about 0.01 wt. % to about2 wt. % or from about 0.2 wt. % to about 0.8 wt. % or from about 0.3 wt.% to about 0.5 wt. % based on the total weight of the reactive modifier,for example.

Alternatively, the reactive modifiers may be formed by grafting in thepresence of an initiator, such as those described above, and a modifierselected from multi-functional acrylate comonomers, styrene,divinylbenzene, triacrylate esters and combinations thereof, forexample. The multi-functional acrylate comonomer may be selected frompolyethylene glycol diacrylate, trimethylolpropane triacrylate (TMPTA),alkoxylated hexanediol diacrylatete, and combinations thereof, forexample. The triacrylate esters may include trimethylopropanetriacrylate esters, for example. It has unexpectedly been observed thatthe modifiers described herein are capable of improving graftingcompared to processes absent such comonomers.

In one or more embodiments, the reactive modifier may include from about80 wt. % to about 99.5 wt. %, or from about 90 wt. % to about 99 wt. %or from about 95 wt. % to about 99 wt. % polyolefin based on the totalweight of the reactive modifier, for example.

In one or more embodiments, the reactive modifier may include from about0.5 wt. % to about 20 wt. %, or from about 1 wt. % to about 10 wt. % orfrom about 1 wt. % to about 5 wt. % grafting component (i.e., theoxazoline, isocyanate, maleic anhydride, acrylic acid derivative) basedon the total weight of the reactive modifier, for example.

In one or more embodiments, the reactive modifier may include from about0.5 wt. % to about 15 wt. %, or from about 1 wt. % to about 10 wt. % orfrom about 1 wt. % to about 5 wt. % modifier based on the total weightof the reactive modifier, for example.

The ratio of grafting component to modifier may vary from about 1:5 toabout 10:1, or from about 1:2 to about 5:1 or from about 1:1 to about3:1, for example.

In one or more embodiments, the reactive modifier may exhibit a graftingyield of from about 0.2 wt. % to about 20 wt. %, or from about 0.5 wt. %to about 10 wt. % or from about 1 wt. % to about 5 wt. %, for example.The grafting yield may be determined by Fourier Transform InfraredSpectroscopy (FTIR) spectroscopy.

The PLA/PO blend may include from about 0.5 wt. % to about 20 wt. %, orfrom about 1 wt. % to about 10 wt. % or from about 3 wt. % to about 5wt. % reactive modifier based on the total weight of the biodegradablepolymeric composition, for example.

Examples of end use articles into which the PLA/PO blend may be formedinclude food packaging, office supplies, plastic lumber, replacementlumber, patio decking, structural supports, laminate flooringcompositions, polymeric foam substrate; decorative surfaces (i.e., crownmolding, etc.) weatherable outdoor materials, point-of-purchase signsand displays, house wares and consumer goods, building insulation,cosmetics packaging, outdoor replacement materials, lids and containers(i.e., for deli, fruit, candies and cookies), appliances, utensils,electronic parts, automotive parts, enclosures, protective head gear,reusable paintballs, toys (e.g., LEGO bricks), musical instruments, golfclub heads, piping, business machines and telephone components, showerheads, door handles, faucet handles, wheel covers, automotive frontgrilles, and so forth. Additional end use articles would be apparent tothose skilled in the art.

In an embodiment, the PP/PLA blends of this disclosure are used toprepare an injection molded article, including, without limitation, aninjection blow molded article. In non-limiting examples, the injectionblow molding process includes forming a pre-form and then biaxiallystretching the pre-form.

In another embodiment, PLA/PO blends are used for the production offilms, including non-oriented, uniaxially oriented, or biaxiallyoriented polylactic acid (BOPLA) films. As used herein, the term“biaxial orientation” refers to a process in which a polymericcomposition is heated to a temperature at or above its glass-transitiontemperature but below its crystalline melting point. Immediatelyfollowing heating, the material may then be extruded into a film, andstretched in both a longitudinal direction (i.e., the machine direction)and in a transverse or lateral direction (i.e., the tenter direction).Such stretching may be carried out simultaneously or sequentially.

In some embodiment, the PLA/PO blend is heated in an extruder. Incertain of these embodiments, the PLA/PO blend may be mixed with aninorganic filler. The PLA/PO blend may be mixed with one or moreinorganic fillers such as calcium carbonate, titanium dioxide, kaolin,alumina trihydrate, calcium sulfate, talc, mica, glass microspheres, orcombinations thereof. The presence of such inorganic fillers may furtherincrease the film opacity at a given film extrusion or stretchingtemperature over that of a film without such a filler, and may alsoextend the temperature window for forming opaque films. The inorganicfillers may be present in an amount of from 1 wt. % to 20 wt. %,alternatively from 1 wt. % to 15 wt. %, or alternatively from 1 wt. % to10 wt. % of the total PLA/PO blend. In certain embodiments, the PLA/POblend is not mixed with an inorganic filler.

The PLA/PO blend is heated in the extruder until molten. The moltenpolymer may then exit through a die and the molten plaque may be used toform an extruded film, a cast film, a biaxially oriented film, or thelike. In an embodiment, the molten plaque may exit through the die andbe taken up onto a roller without additional stretching to form anextruded film. Alternatively, the molten plaque may exit through the dieand be uniaxially stretched while being taken up onto a chill rollerwhere it is cooled to produce a cast film.

In an embodiment, the molten plaque exits through the die and is passedover a first roller (e.g., a chill roller) which solidifies the PLA/POblend into a film. Then, the film may be biaxially oriented bystretching such film in a longitudinal direction and in a transversedirection. The longitudinal orientation may be accomplished through theuse of two sequentially disposed rollers, the second (or fast roller)operating at a speed in relation to the slower roller corresponding tothe desired orientation ratio. Longitudinal orientation mayalternatively be accomplished through a series of rollers withincreasing speeds, sometimes with additional intermediate rollers fortemperature control and other functions.

After longitudinal orientation, the film may be cooled, pre-heated andpassed into a lateral orientation section. The lateral orientationsection may include, for example, a tenter frame mechanism, where thefilm is stressed in the transverse direction. Annealing and/oradditional processing may follow such orientation. Alternatively, thefilm may be stretched in both directions at same time.

In some embodiments, the BOPLA film made from the PLA/PO blend isstretched in the longitudinal direction, the transverse direction orboth at a temperature of equal to or less than 120° C., or from 65° C.to 120° C., or from 70° C. to 110° C., or from 70° C. to 90° C. Incertain embodiments, the stretch speed in the making of the BOPLA filmis up to 500 m/min, or up to 300 m/min of from 0.1 to 500 m/min in thelongitudinal direction, the transverse direction or both.

Additional disclosure on biaxial film production may be found in U.S.Pat. No. 4,029,876 and U.S. Pat. No. 2,178,104, each of which isincorporated by reference herein in its entirety.

In certain embodiments of the disclosure, BOPLA films are opaque.“Opaque” refers to a film with greater than or equal to 80% haze, asmeasured by ASTM-D1003. In certain embodiments of the presentdisclosure, the BOPLA film has a haze of great than 80%, greater than90%, greater than 95%, greater than 99% or about 100% as measured byASTM-D1003. In certain embodiments of the present disclosure, the BOPLAfilm, when stretched biaxially at an oven temperature of above 80° C.,has a haze of great than 80%, greater than 90%, greater than 95%,greater than 99% or about 100% as measured by ASTM-D1003. In certainembodiments of the present disclosure, the BOPLA film, when stretchedbiaxially at an oven temperature of from about 80° C. to about 90° C.,has a haze of great than 80%, greater than 90%, greater than 95%,greater than 99% or about 100% as measured by ASTM-D1003. In someembodiments, the BOPLA films have a 45° gloss of less than 50%, lessthan 30%, less than 20% or less than 10% as measured by ASTM-D-2457.

In certain embodiments, the BOPLA films are single layer films. In otherembodiments, the BOPLA films prepared from PLA/PO blends may form one ormore layers of a multilayer film. The additional layers of themultilayer film may be any coextrudable film known in the art, such assyndiotactic polypropylene, low density polyethylene, linear low densitypolyethylene, medium density polyethylene, high density polyethylene,ethylene-propylene copolymers, butylenes-propylene copolymers,ethylene-butylene copolymers, ethylene-propylene-butylene terpolymers,ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers,nylons, and the like, or combinations thereof.

EXAMPLE

The disclosure having been generally described, the following exampleshows particular embodiments of the disclosure. It is understood thatthe example is given by way of illustration and is not intended to limitthe specification or the claims.

Samples of NatureWorks PLA4042 were blended with 5% and 10% TotalPetrochemicals HDPE 7194 compounded and cast into 16 mil sheets. A“neat” sample, of NatureWorks PLA4042, i.e., without a polyolefin, wasalso cast into a 16 mil sheets. No inorganic fillers were used in any ofthe films. The neat PLA and PLA/HDPE blends were stretched bi-axially ata 3×3 areal draw ratio within an oven temperature range from 70° C. to110° C. at 5° C. temperature increments on a Bruckner Karo IV labstretcher to form a white opaque film. The film samples were tested forhaze and 45° gloss. Results for haze are shown below in TABLE 1. Resultsfor gloss are shown below in TABLE 2. Results are graphically shown inFIGS. 1A and 1B, respectively. Haze was measured using ASTM-D1003. Glosswas measured using ASTM-D-2457.

TABLE 1 PLA4042/ PLA4042/ Haze PLA4042 5% HDPE7194 10% HDPE7194 70 1.7100 100 75 1.5 100 100 80 0.5 97 100 85 0.6 89 100 90 0.6 81 100 95 0.679 98 100 1.1 82 95 105 1.4 88 94 110 1.3 90 94

TABLE 2 PLA4042/ PLA4042/ Gloss PLA4042 5% HDPE7194 10% HDPE7194 70 7825 17 75 78 20 15 80 82 24 17 85 82 19 18 90 80 19 16 95 81 13 12 100 8110 5 105 78 7 5 110 73 5 5

While various embodiments have been shown and described, modificationsthereof can be made by one skilled in the art without departing from thespirit and teachings of the disclosure. The embodiments described hereinare exemplary only, and are not intended to be limiting. Many variationsand modifications of the subject matter disclosed herein are possibleand are within the scope of the disclosure. Where numerical ranges orlimitations are expressly stated, such express ranges or limitationsshould be understood to include iterative ranges or limitations of likemagnitude falling within the expressly stated ranges or limitations(e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than0.10 includes 0.11, 0.12, 0.13, etc.).

1-12. (canceled)
 13. A method of producing a biaxially oriented filmcomprising: blending a polylactic acid (PLA) and a polyolefin (PO) toform a polymeric blend (PLA/PO blend) having a ratio of PLA to PO in thePLA/PO blend between 4:1 and 199:1, wherein the polyolefin is apolyethylene, forming the PLA/PO blend into a film, and biaxiallyorienting the film to form a film having a haze of 80% or greater asmeasured by ASTM-D1003 and a 45° gloss of less than 50% as measured byASTM-D-2457.
 14. The method of claim 13, wherein the step of biaxiallyorienting the film comprises stretching the film in the longitudinaldirection, the transverse direction or both at a temperature of between65° C. to 120° C.
 15. The method of claim 13, wherein the step ofbiaxially orienting the film comprises stretching the film in thelongitudinal direction, the transverse direction or both at a stretchspeed of less than or equal to 500 m/min.
 16. The method of claim 13further comprising prior to the step of forming the PLA/PO blend intothe film: adding a compatibilizer to the PLA/PO blend.
 17. The method ofclaim 13 further comprising prior to the step of forming the PLA/POblend into the film: adding a reactive modifier to the PLA/PO blend. 18.The method of claim 13 further comprising prior to the step of formingthe PLA/PO blend into the film: adding an inorganic filler to the PLA/POblend.
 19. The method of claim 18, wherein the inorganic filler iscalcium carbonate, titanium dioxide, kaolin, alumina trihydrate, calciumsulfate, talc, mica, glass microspheres, or combinations thereof.
 20. Anarticle comprising: a polylactic acid (PLA) and polyolefin (PO) blendhaving a ratio of PLA to PO in the PLA/PO blend of between 4:1 and199:1, wherein the polyolefin is a polyethylene, and wherein the articleis opaque.
 21. The article of claim 18 further comprising acompatibilizer, wherein the compatibilizer content in the PLA/PO blendis between 0.2% and 30% by weight of the PLA/PO blend.
 22. The articleof claim 18 further comprising a reactive modifier.
 23. A blendcomprising: a polylactic acid (PLA) and a polyolefin (PO), wherein thepolyolefin is a polyethylene, and wherein the blend includes between 80and 99.5 weight percent of the PLA.